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Re: Kevlar skin on frame?
By:Bruce Schultz
Date: 8/8/2001, 8:43 am
In Response To: Re: Kevlar skin on frame? (Paul G. Jacobson)

: Expense is obvious? :)

: Face it unless you can get the fabric for free, whether you cover the boat
: with kevlar, or cotton, you gotta pay something. Subtract the cost of a
: canvas covering from what you pay for the kevlar and you may find the
: difference is not too bad.

: A lot more depends on the strength of the fabric, not on the chemical makeup
: of the fibers. A very thin piece of kevlar, say something in the 1 ounce
: per square yard or lighter range, might not be as strong as a piece of 20
: ounce nylon, polyester, or fiberglass.

: At the same time, consider that the thickness of the waterproofing material
: might depend on the thickness of the fabric on which it is applied. A
: piece of cotton duck that is .08 inches thick and is saturated with a
: rubber compound will give you a rubber layer that is also .080 inches (80
: thousandths) thick, while a superstrong synthetic which has the same
: strength as that cotton duck maight be only .010 thick (10 thousandths).
: If you saturate the thinner fabric and have a rubber layer that is only
: .010 thick it might be more easily abraded, or perforated. If that
: happened then although the fabric doesn't rip, you would get lots of
: pinhole leaks. You could keep applying the waterproof coating to the
: surface of this material, and build up a thick coating, but the additional
: layers of rubberized material would not be reinforced, so there would be
: no increase in strength, but the weight would come close to that of the
: cotton duck covering.

: So, Kevlar is good if it is strong enough, and thick enough. Don't buy the
: thinnest you can find unless you are looking for a special purpose,
: extremely lightweight, and rather delicate boat. Are we thinking a
: backpacking boat here?

: Assuming it is ok to cover a

: It should be simpler. Since there is no wood structure under it, you don't
: have to worry about forcing the resin through the fabric. There is no
: underlying wood to act like a sponge and suck away the resin, either. A
: roller would probably put on a nice even coating, which would soak into
: the fibers and weave. I'd just paint the resin on, and then go to the
: inside and brush away any drips I could reach with a (mostly) dry foam
: brush.

: It might be worthwhile to try a sample first. If you can coat the interior
: surface of the cloth before attaching the skin you would have a stiffer
: material to work with, but the inside would be completely covered.
: applying that stiffer material to the frame you would need to slit it in
: several places to get it to follow the lines of the boat, but these cuts
: could be overlapped and glued with epoxy resin, and reinforced with an
: additional strip of your kevlar and resin.

: The kevlar should go rather clear, and probably somewhat yellow in color.
: Carry your gear is brightly colored gear bags and it should look rather
: pretty. Or, add a pigment to the epoxy resin.

: As long as you are using epoxy resin, coat the frame with 1 or 2 coats and
: let it setup for a few days before you cover it.

: You may want to coat the boat with a UV blocking varnish if you have not
: added solid pigment to the epoxy resin.

: hope this helps.

I think you might want to get a kevlar with a tight weave not the kind you get at a normal supply house. I have a roll of around 3 oz material which may have been made for aircraft wings ? It is very hard to wet out on laminating applications but it would seem to be ideal for skin boats. I would not seal it with epoxy as the material stiffens up and reduces its resistance to tearing. I can not cut it with hardly anything as a fabric but when I coat it with epoxy it cuts almost as easy as glass. So I would try coating it with neoprene and hypolon as with a normal skin boat. I do not know were to obtain the tight weave cloth but it would be worth checking into. I assume it is very expensive.

Messages In This Thread

Kevlar skin on frame?
Kurt -- 8/6/2001, 2:01 pm
Re: Kevlar skin on frame?
Don -- 8/7/2001, 3:59 pm
Re: Kevlar skin on frame?
David Dick -- 8/7/2001, 8:37 am
Re: Kevlar skin on frame?
Paul G. Jacobson -- 8/8/2001, 2:58 am
Re: Kevlar skin on frame?
David Dick -- 8/8/2001, 9:55 am
Re: Kevlar skin on frame?
Paul G. Jacobson -- 8/8/2001, 7:28 pm
Re: Kevlar skin on frame?
kurt -- 8/6/2001, 11:40 pm
Re: Kevlar skin on frame?
Brian Nystrom -- 8/7/2001, 12:31 pm
Re: Kevlar skin on frame?
Paul G. Jacobson -- 8/6/2001, 11:08 pm
Re: Kevlar skin on frame?
Bruce Schultz -- 8/8/2001, 8:43 am
Re: Kevlar skin on frame?
Scotty -- 8/7/2001, 7:16 am
Re: Kevlar skin on frame?
Roger Tulk -- 8/6/2001, 9:10 pm
Re: Kevlar skin on frame?
Paul G. Jacobson -- 8/6/2001, 11:11 pm
Glass skin on frame
Jim -- 8/7/2001, 9:50 am
Re: Glass skin on frame
Tony -- 8/7/2001, 1:10 pm
Re: Glass skin on frame
Jim -- 8/7/2001, 3:09 pm